In the art of self-propelled combines which use different heads, for example, for combining grain and for picking and shelling corn, the substantial width of the head frequently requires that the head be separately transported in a longitudinal direction on a road transport trailer, for example, of the general type as disclosed in U.S. Pat. No. 5,333,904. In order for the transport trailer to accommodate and support the different heads of different manufacturers of self-propelled combines, the trailer preferably has upper and lower elongated support bars which extend longitudinally on opposite sides of the trailer. A pair of support brackets are slidably mounted on each of the bars, and each bracket is adjustable. As disclosed in the above mentioned patent, each of the support brackets on the lower bar has one L-shaped support surface for receiving a frame member on one type of combine head. A second support member pivots from an inactive position to an active position on top of the first support member and has a curved surface for receiving a cylindrical frame member of another combine head.
In such a transport trailer of the general type disclosed in the above mentioned patent, it is desirable to have support members with several conveniently selectable different head engaging surfaces for accommodating a variety of different combine heads of different manufacturers and for accommodating the different heads of each manufacturer. Such features are especially desirable on transport trailers used by farm machinery distributors and dealers who frequently transport a wide variety of combine heads. It is also desirable for the transport trailer to provide a head hold down unit which may be conveniently used and also adapted for accommodating a wide variety of combine heads.